Motor Insulation resistance was bad
Motor Insulation resistance was bad
(OP)
Dear All,
Please, I need some advice,
I have a problem with my motor. The motor with 380 V, 3 phase, 50 Hz, 2 pole, 150kW suddenly shutdown after running around 2 hours. The 50G relay (groundfault relay) was actived. I measured insulation resistance by 500VDC and winding resistance , result :
R phase 2.55 Mohm/ 0.0135 ohm
S phase 2.50 Mohm/ 0.0136 ohm
T phase 2.60 Mohm/ 0.0135 ohm
Based on this, I started motor again until 4 hours and I measured current (ampere) and voltage each phase were normal and vibration was normal ( there was nothing electrical problem ). Vibration at 2H (maximum value) overall below 1.5 mm/s RMS. I take with Fmax 200 Hz and resolution 6400 lines.
I stopped motor and I measured insulation resistance was increased each phase around 50 Mohm. I conducted heating up the motor until insulation resistance reach 150 Mohm.
After 3 days, I checked insulation resistance and I got insulation resistance were decrease (each phase) become 3.50 Mohm
Would you like to explain me:
What is problem with my motor?
Why insulation resistance decrease in 3 days?
Please, give me some advice for this condition.
Regards,
pjono
Please, I need some advice,
I have a problem with my motor. The motor with 380 V, 3 phase, 50 Hz, 2 pole, 150kW suddenly shutdown after running around 2 hours. The 50G relay (groundfault relay) was actived. I measured insulation resistance by 500VDC and winding resistance , result :
R phase 2.55 Mohm/ 0.0135 ohm
S phase 2.50 Mohm/ 0.0136 ohm
T phase 2.60 Mohm/ 0.0135 ohm
Based on this, I started motor again until 4 hours and I measured current (ampere) and voltage each phase were normal and vibration was normal ( there was nothing electrical problem ). Vibration at 2H (maximum value) overall below 1.5 mm/s RMS. I take with Fmax 200 Hz and resolution 6400 lines.
I stopped motor and I measured insulation resistance was increased each phase around 50 Mohm. I conducted heating up the motor until insulation resistance reach 150 Mohm.
After 3 days, I checked insulation resistance and I got insulation resistance were decrease (each phase) become 3.50 Mohm
Would you like to explain me:
What is problem with my motor?
Why insulation resistance decrease in 3 days?
Please, give me some advice for this condition.
Regards,
pjono





RE: Motor Insulation resistance was bad
Maybe opening the motor to do cleaning and service would help. You could open one cover (depending on the IP-degree, though) and use your flashlight to look if it sounds reasonable.
Does this make sense to your application?
RE: Motor Insulation resistance was bad
Yes, after 3 days, IR was become low again.
Whait is "use flashlight" mean, Sir?
Would you like to explain about that, please?
Thanks
RE: Motor Insulation resistance was bad
RE: Motor Insulation resistance was bad
Yes, motor in outdoors.
Thank you for your explanation.
Any way, thank you for all to give me some advice.
Regards
jonos
RE: Motor Insulation resistance was bad
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